Tubeless tire repair plug insertion technique

ABSTRACT

A repair plug insertable by a pneumatic gun or other tool into a puncture formed in the casing of a tubeless tire, thereby to seal the puncture. The plug is constituted by a core of cured rubber coated with a tacky layer of vulcanizable rubber which, when subjected to the heat produced by a running tire, vulcanizes in place and bonds to the tire casing. Before being inserted in the puncture, the plug is coated with a temporary detackifying compound which lubricates the passage of the plug through the inserting tool. The compound is dissolvable in rubber when subjected to the heat of the running tire so that it disappears in the plug and the bonding action of the tacky coating thereon is permitted to proceed.

United States Patent [72] Inventors Franklin G. Reick 228 W. Place,Westwood, NJ. 07675; Robert S. Hanser, P.0. Box 338, Saddle River, NJ.07458 [21] App1.No. 796,712 [22] Filed Feb. 5, 1969 [45] Patented Oct.26, 1971 [54] TUBELESS TIRE REPAIR PLUG INSERTION TECHNIQUE 5 Claims, 5Drawing Figs. [52] US. Cl 156/95, 152/370 [51] Int. Cl B60c 21/06 [50]Field of Search 156/94, 95, 96, 97, 98; 152/370 [5 6] References CitedUNITED STATES PATENTS 2,966,189 12/1960 Chambers et a1. 152/3702,990,736 7/1961 Crandall 152/370 Primary Examiner-Benjamin A. BorcheltAssistant Examiner-Daniel Bent Attorney-Michael Ebert ABSTRACT: A repairplug insertable by a pneumatic gun or other tool into a puncture formedin the casing of a tubeless tire, thereby to seal the puncture. The plugis constituted by a core of cured rubber coated with a tacky layer ofvulcanizable rubber which, when subjected to the heat produced by arunning tire, vulcanizes in place and bonds to the tire casing. Beforebeing inserted in the puncture, the plug is coated with a temporarydetackifying compound which lubricates the passage of the plug throughthe inserting tool. The compound is dissolvable in rubber when subjectedto the heat of the running tire so that it disappears in the plug andthe bonding action of the tacky coating thereon is permitted to proceed.

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TUBELESS TIRE REPAIR PLUG INSERTION TECHNIQUE This invention relatesgenerally to plug techniques for repairing tubeless tires, and moreparticularly to a technique for facilitating the insertion of a rubberplug into a tire puncture without interfering with the ability of theplug to bond to the tire and thereby effectively seal the puncture.

It is now the widespread practice to effect repairs in a tubeless tireby inserting a rubber plug in the puncture or other injury. Plugs formedsolely from cured rubber will not readily vulcanize; hence plugs 'ofthis construction will not bond effectively tothe cured rubber of thetire casing, even with the application of hat or by the use of avulcanizing cement.

To overcome this difficulty,'it is the present practice to form the plugwith an uncured rubber layer which is coated over a cured rubber core.After insertion of the plug in the puncture, the uncured rubber layerwill vulcanize, in situ, when subjected to the heat developed by therunning tire.

In order to insert a plug of this type in the tire, use is generallymade of a pneumatic gun adapted to drive the plug under high pressureinto the puncture. The plug is in rivet form, being provided with amushroomlike head and a long stern. ln loading a pneumatic gun designedfor such plugs, the plug is forced, stem-first, into the barrel of thegun. When the fun is fired, the plug is ejected under air pressure intothe puncture, with the head of the plug penetrating the interior of thecasing.

To prevent the plug from jamming in the pneumatic gun, its surface mustbe adequately lubricated. A lubricant has been found to be essential,for the high-pneumatic forces created by the gun cause the rubber of theplug to flow and elongate. The current trade practice in this regardinvolves coating the rubber plug at the factory with a filmof siliconeoil or another long-lasting lubricant which is not soluble in rubber andwill remain indefinitely on the surface of the plug. While suchlubricants carry out their proper function in the gun, which is tofacilitate ejection of the plug, they continue to lubricate the plugafter insertion in the tire.

This continued lubrication has adverse effects which may be quiteserious, in that it inhibits effective bonding of the plug to thecasingof the tire, for the lubricating film acts permanently as a partingagent or barrier between the plug and easing.

This creates a situation which is potentially very hazardous, for allthat holds the plug in place is the internal air pressure exerted on thehead of the plug. This peril has beenrecognized by the RubberManufacturer's Association which has issued warnings against the use ofrubber repair plugs. The Association has pointed out that such plugs arenot reliable and has recommended that their use be limited to temporaryrepairs in emergencies, but not otherwise. When considering thatliterally millions of rubber repair plugs are sold every year throughoutthe world, it will be appreciated that the danger involved is of majorconcern.

In view of the foregoing, it is the main object of this invention toprovide a repair plug and a lubricant therefor which obviates thedrawbacks incident to conventional repair techniques, and which may bereadily inserted in a tubeless tire and effectively bonded thereto.

Also an object of the invention is to provide a washer patch which maybe used in conjunction with a rubber plug to effect repairs of punctureswhose damaged area on the interior of the casing is greater than thehead of the plug.

Briefly stated, in a technique in accordance with the invention, use ismade of a repair plug whose cured rubber core is coated with a tackylayer of vulcanizable rubber, the plug, before being loaded in theinsertion tool, being covered with a temporary detackifying compoundacting as a lubricant. The detackifying compound is chosen from a classof materials which are highly soluble in rubber and which will beabsorbed therein when the temperature thereof is elevated toapproximately l F. Thus, after insertion of the plug, when the lubricantis subjected to the heat of the running tire, it disappears into therubber and the vulcanizable layer on the plug proceeds to vulcanize inplace and bond to the tire to create a reliable seal which remainseffective during the life of the tire.

For a better understanding of the invention, as well as'other objectsand features thereof, reference is made to the following detaileddescription to be read in conjunction with the accompanying drawing,wherein:

FIG. 1 is an elevational view of a rubber repair in a technique inaccordance with the invention,

FIG. 2, in section, shows the plugafier insertion in a puncture in thecasing of a tubeless tire,

FIG. 3 shows, in plan view, a washer in accordance with the invention tobe used in conjunction with a repair plug,

FIG. 4 is a sectional view of the washer, and

FIG. 5 shows the washer and plug combination when installed in a tire. 1

plug for use THE REPAIR TECHNIQUE Referring now to FIG. 1, there isshown a rubber plug 10 in accordance with the invention, the plug havinga strong core 10A of cured rubber and a coating 10B thereover of tackyvulcanizable material. The plug is rivet-shaped-so that it has amushroom head and a relatively long stem whose length is greater thanthe thickness of any existing tire casing. Small and medium puncturesgenerally require a 56-inch plug while larger punctures call for aseven-sixteenth-inch plug. in practice, after insertion, the excessportion of the stem projecting from the casing is cut ed.

The core 10A of the plug is manufactured by conventional moldingtechniques well known in the art. After manufacture, the plugs arewashed and tumbled in a detergent solution to remove oil and othersurface contaminants arising from the molding operation.

The cleaned plugs are carefully dried and then dipped in a solventsolution producing the desired vulcanizable coating 108. A preferredform of high-tack solution for dip-coating mushroom plugs has thefollowing composition:

' 2 pounds Crumb Rubber one-half pound Zinc Oxide one-half poundTackifying Resin one-half pound Soluble Sulfur Compounds 3 gallonsl-lexane l quart Toluene 10 grams Ultra Accelerator one-half ChlorinatedPolyphenols Afier the solvent has evaporated, the tacky plugs are thenboxed for subsequent use. It is to be understood that the invention isnot limited to the above coating and that eristing vulcanizable coatingsmay be used on the plug. Alternatively, the plugs may be made entirelyof natural rubber.

in field use, the plugs are inserted in tire punctures, using anyexisting fonn of air gun or tool such as those manufactured by TylerManufacturing Company. As pointed out previously, the tacky surfacemakes it impossible for the plugs to go through the inserting tool.Thereafter, before placing the plug into the tool, the plug is rubbedwith a surface-active lubricant in accordance with the invention thattemporarily renders the surface very slippery.

Before inserting the plug in the puncture or tire injury, the wallsurrounding the puncture is made wet, using a conventional rubber cementfor this purpose. The cement may be introduced by means of a probedipped into the cement solution.

The detackifying lubricant is chosen from a class of materials that arehighly soluble in rubber and will be absorbed thereby when thetemperature is elevated to about l00 F. This temperature is quicklyreached in a running tire. Thus as shown in FIG. 2, plug 10 is insertedin a puncture II in a casing 12, the head of the plug lying against theinterior surface of the case. As the tire operates, the tacky layer 108on the plug which has absorbed the lubricant again becomes very sticky,and eventually vulcanized under the influence of the heat, therebybonding to and becoming part of the tire.

if the injured area inside the tire is greater than the head of theplug, a washer-shaped patch 13 is glued in place over this area. Thewasher is constituted by a rubber back 14 and a cushion base 15, thewasher having a central hole 16 through which the head of plug entersthe casing. The diameter of the hole is about the same as the stem ofthe plug. Thus the plug head is prevented by the washer from beingpushed out of the tire.

LUBRICANT The requisite lubricant is one which has a desired degree oflubricity as well as solubility in the rubber to promote its eventualdisappearance and the return of surface tackiness. Additional propertieswhich are desirable are low toxicity, low cost and ease of handling.Compounds suitable for this purpose fall into three broad classes,namely A Liquid, B Paste, and C waxy Solid. The table below gives someexamples of these compounds which have been tested with acceptableresults.

(Class A Liquid Polyoxyethylene (20) Sorbitan Monopalmitate EthoxylatedOleamide Bis (Z-hydroxyethyl) Stearylarnine Oxide (glass 13 Paste)l-(2-Hydroxyethyl)-2-Heptadecenyl-Z-lmidazoline Best N-Tallowl,2diaminopropane dioleate N-Tallow-1 ,3, diaminopropane acetate where Rdenotes an alkyl group derived from a suitable fatty acid.

These compounds contain both primary and secondary amine groupings.They-are strong organic bases and exhibit great cationic activity. Theability to be absorbed onto rubber surfaces is enhanced by thepolar-amino groups.

For safety in handling the amides are reacted with organic acids to formthe surface active salts that are used as our disappearing lubricants.They have low toxicity and are easily handled. The compounds can beblended to give the desired paste at room temperature.

While there has been shown and described a preferred embodiment of atubeless tire repair-plug-insertion technique, in accordance with theinvention, it will be appreciated that many changes and modificationsmay be made therein without, however, departing from the essentialspirit of the invention as defined in the annexed claims.

We claim:

1. in the technique for repairing a tubeless tire by means of a rubberplug which is insertable in a puncture by a pneumatic tool, said plughaving a core of cured rubber and a tacky coating thereover ofVulcanizable rubber, whereby the plug, when the tire is heated, proceedsto vulcanize and bond to the tire to seal the puncture, the steps of:

A. coating the surface of the rubber plug with a temporary lubricantconstituted by a detackifying agent which is dissolvable in the rubberwhen its temperature is at least about F.,

B. loading the tool with the lubricated plug and firing the plug intothe puncture, the passage of the plug through the tool being facilitatedby the lubricant, C. and running the plugged tire to create heatelevating the cant is a compound which is liquid at room temperature andis of low toxicity and high lubricity.

4. in a technique, as set forth in claim 1, wherein said lubricant is acompound which is a paste at room temperature and is of low toxicity andhigh lubricity, said compound being derived from fatty diamines.

5. In a technique, as set forth in claim 1, wherein said lubricant is awaxy solid at room temperature and is of low toxicity and highlubricity.

2. In a technique as set forth in claim 1, wherein said tacky coating isapplied by dipping the core into a rubber solution including atackifying resin and soluble sulfur compounds.
 3. In a technique, as setforth in claim 1, wherein said lubricant is a compound which is liquidat room temperature and is of low toxicity and high lubricity.
 4. In atechnique, as set forth in claim 1, wherein said lubricant is a compoundwhich is a paste at room temperature and is of low toxicity and highlubricity, said compound being derived from fatty diamines.
 5. In atechnique, as set forth in claim 1, wherein said lubricant is a waxysolid at room temperature and is of low toxicity and high lubricity.